High-silicon aluminum alloy electronic packaging shell and manufacturing method thereof

Abstract

Disclosed is a method of manufacturing a high-silicon aluminum alloy electronic packaging shell, which uses high-silicon aluminum alloys with different silicon content as a bottom, transition part(s) and a welding part respectively to form a gradient material structure to meet the comprehensive requirements of electronic packaging materials for material properties such as strength, thermal conductivity, and thermal expansion coefficient, as well as process properties such as machining, surface coating, and laser welding.

What is claimed: 
     
         1 . A method of manufacturing an electronic packaging shell, comprising the steps of:
 S1: designing a silicon aluminum alloy gradient material ingot and a size of the electronic packaging shell; the gradient material ingot comprises a connection layer, transition layer(s) and a welding layer, the transition layer(s) is located between the connection layer and the welding layer, the number of the transition layer(s) is ≥0, and the gradient material ingot has a silicon content gradient that decreases along a direction from the connection layer to the welding layer; the electronic packaging shell comprises a bottom and a side wall, the bottom and the side wall are enclosed to form a holding space, the side wall is composed of transition part(s) and a welding part, the transition part(s) is located between the bottom and the welding part, and the number of the transition part(s) is ≥0;   S2: using silicon aluminum alloys with different silicon contents as raw materials, and depositing the connection layer, the transition layer(s) and the welding layer in sequence by atomized spray deposition process to form the gradient material ingot designed by the step S1;   S3: densifying the gradient material ingot;   S4: cutting the gradient material ingot into the electronic packaging shell; the bottom is formed by cutting the connection layer, and the side wall is formed by cutting the transition layer(s) and the welding layer; and   S5: annealing the electronic packaging shell.   
     
     
         2 . The method of  claim 1 , wherein the step S1 comprises: (1) detecting quantitative relationships between silicon content and material properties and process properties of silicon aluminum alloy; (2) referring to temperature and thermal stress distribution of known typical silicon aluminum alloy electronic packaging shell, and according to the quantitative relationships, designing respective composition and thickness of the bottom, the transition part(s) and the welding part. 
     
     
         3 . The method of  claim 2 , wherein in the step (1), the material properties comprise tensile strength, hardness, thermal conductivity and thermal expansion coefficient, and the process properties comprise machining, surface plating and laser welding. 
     
     
         4 . The method of  claim 2 , wherein the step (2) comprises: setting a preset composition and a preset thickness of the bottom and a preset composition of the welding part, then taking the preset composition and the preset thickness of the bottom and the preset composition of the welding part as known quantities, calculating and designing the composition and thickness of the transition part(s) and the thickness of the welding part by using thermoelastic theory and finite element method, then taking the composition and the thickness of the transition part(s) and the thickness of the welding part as known quantities, calculating and designing the composition and the thickness of the bottom and the composition of the welding part by using thermoelastic theory and finite element calculation. 
     
     
         5 . The method of  claim 1 , wherein in the step S2, the atomized spray deposition process adopts a melting temperature of 1200-1500° C. and nitrogen gas with a pressure of 0.7-1.2 MPa for spraying. 
     
     
         6 . The method of  claim 1 , wherein in the step S3, the gradient material ingot is densified by one of hot isostatic pressing, hot pressing sintering and spark plasma sintering, and a densification temperature of 480-550° C., a holding time of 1-4 hours, a heating rate of 10-40° C./hour and a cooling rate of 20-50° C./hour are adopted. 
     
     
         7 . The method of  claim 1 , wherein: in the step S5, an annealing temperature of 320-440° C. and a holding time of 6-24 hours are adopted, and a pressure of 0.5-5 MPa is applied above the electronic packaging shell during annealing. 
     
     
         8 . The method of  claim 1 , further comprising S6: characterizing the electronic packaging shell, and cycling the steps S1-S5 according to characterization results to optimize the respective composition and thickness of the bottom, the transition part(s) and the welding part. 
     
     
         9 . The method of  claim 1 , wherein a silicon mass content of the connection layer is 50-70%, a silicon mass content of the transition layer(s) is 35-50%, and a silicon mass content of the welding layer is 12-35%. 
     
     
         10 . An electronic packaging shell, comprising a bottom and a side wall; the bottom and the side wall are enclosed to form a holding space, the side wall is composed of transition part(s) and a welding part, the transition part(s) is located between the bottom and the welding part, and the number of the transition part(s) is ≥0;
 the electronic packaging shell is formed from silicon aluminum alloys with different silicon contents as raw material through atomized spray deposition process, densification, annealing and cutting, and has a silicon content gradient that decreases along a direction from the bottom to the welding part. 
 
     
     
         11 . The electronic packaging shell of  claim 10 , wherein a silicon mass content of the bottom is 50-70%, a silicon mass content of the transition part(s) is 35-50%, and a silicon mass content of the welding part is 12-35%.